The Feingold Diet, which eliminates the consumption of artificial food colorings and flavorings, has been reported, on a clinical basis, to reduce symptomatology in hyperactive children. This study will evaluate the role of artificial food colorings on hyperactive symptomatology. Children to be studied will be hyperactive children who are reported to have responded to the Feingold diet. These children, maintained on the Feingold diet, will be challenged in a double-blind crossover design with placebo cookies (all natural ingredients) and challenge cookies (containing all commonly used artificial food colorings). Evaluation will include school and parental reports, psychiatric evaluation, and a test of distractibility. Data analysis will compare the active and placebo conditions.